PCR-SSCP检测胃癌中p53基因突变

目的　研究p5 3基因表达及突变在胃癌发生中的地位。方法　采用链霉菌抗生物素蛋白 -过氧化酶 (S -P)法与聚合酶链反应 -单链构象多态性 (PCR -SSCP)分析技术分别检测胃癌p5 3基因表达及突变。结果　p5 3蛋白表达在正常胃粘膜均为阴性 (0 / 2 0 ) ,在不典型增生为 18% (11/ 6 0 ) ,其中轻度全为阴性(0 / 2 0 ) ,中度 2 5 % (5 / 2 0 ) ,重度 30 % (6 / 2 0 ) ,明显低于胃癌的 5 8% (70 / 12 0 ) (P <0 .0 5 ) ,而中度、重度不典型增生高于正常胃粘膜及轻度不典型增生 (P <0 .0 5 )。胃癌中p5 3基因第 5外显子突变率高达 2 5 % (5 / 2 0 ) ,显著高于无突变的正常胃粘膜 0 % (0 / 2 0 ) (P <0 .0 5 )。结论　p5 3基因突变可出现于中度、重度不典型增生 ,是胃癌发生的一个早期事件。在胃癌发生中p5 3基因第 5外显子突变频繁

Mutation Detection of p53 Gene by PCR-SSCP in Gastric Carcinoma

Objectives: To investigate the relationship between expression of p53 gene and gastric carcinogenesis, and to evaluate the role of p53 gene mutation in exon 5 in gastric carcinoma. Methods: The expression and mutation of p53 gene in exon 5 were respectively examined by streptavidin-peroxidase conjugated method (S-P) and polymerase chain reaction-single strand conformation polymorphism analysis (PCR-SSCP) in gastric carcinoma. Results: Complete absence of p53 protein expression was observed in normal gastric mucosa; p53 immunopositivity was detected in 18% (11/60) of the dysplasias, mild dysplasias were all negative,25%(5/20) of moderate and 30%(6/20) of severe dysplasias were positive, lower than 58%(70/120) of gastric carcinomas respectively(P<0.05).The difference between moderate or severe dysplasia and normal mucosa or mild dysplasia were significant (P<0.05). The frequency of p53 mutation in exon 5 was 25%(5/20) and much higher than that of normal gastric mucosas without mutation (P<0.05).Conclusions: Expression of p53 protein shows the increasing frequency from moderate and severe dysplasia to gastric carcinoma . Mutation of p53 gene is an early event, and p53 mutation in exon 5 is frequent in gastric carinogenesis.